Characterisation of the eclipsing post-common-envelope binary TIC 60040774

TL;DR

This paper characterizes the eclipsing post-common-envelope binary TIC 60040774, revealing detailed stellar parameters and highlighting the need for further high-cadence observations to understand its eclipse profile and potential circumbinary planets.

Contribution

It provides the first detailed characterization of TIC 60040774 using TESS, SALT, and multi-band photometry, including mass, temperature, and orbital parameters.

Findings

Orbital period of approximately 0.405 days.

White dwarf mass around 0.598 solar masses.

Secondary M6.5 dwarf with temperature ~2759 K.

Abstract

Binaries with a white dwarf primary and a main sequence secondary can be used to test our understanding of both single and binary star evolution. A small fraction of such systems experienced a common-envelope phase from which they emerged with a relatively short orbital period. Here, we present the characterisation of an eclipsing post-common-envelope binary of this kind, TIC 60040774, based on the light curve provided by the Transiting Exoplanet Survey Satellite (TESS), multi-band photometry collated from the virtual observatory, and spectroscopic data obtained the Southern African Large Telescope (SALT). With an orbital period of $0.404807\pm0.000149$ days, this system consists of a young white dwarf paired with an M6.5 dwarf companion. We estimate the masses of the primary and secondary to be $0.598\pm0.029$ M$_{\odot}$ and $0.107\pm0.020$ M$_{\odot}$, while the effective temperatures are $14050\pm360$ K and $2759\pm50$ K, respectively. The eclipse ingress and egress profile is shallower than expected from a simple geometric model such that more precise high-cadence photometry is required to understand the nature of this system. Given the similarity of TIC 60040774 to systems like GK Vir and NN Ser, it will be worth tracking its eclipse times to check for the presence of one or more circumbinary planets.